Semiconductor device having capacitor and manufacturing method thereof

ABSTRACT

A semiconductor device and a manufacturing method thereof are provided. The method includes forming an isolation structure in a substrate to define an isolating region and forming a capacitor structure on an upper surface of the isolation structure and comprising a first semiconductor structure and a second semiconductor structure separated by an insulator pattern. The first semiconductor structure and the second semiconductor structure are formed with upper surfaces aligned with one another.

REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. application Ser. No.17/106,409, filed on Nov. 30, 2020, which is a Continuation of U.S.application Ser. No. 16/273,260, filed on Feb. 12, 2019 (now U.S. Pat.No. 10,868,108, issued on Dec. 15, 2020), which claims the benefit ofU.S. Provisional Application No. 62/690,430, filed on Jun. 27, 2018. Thecontents of the above-referenced patent applications are herebyincorporated by reference in their entirety.

BACKGROUND

Following the rapid progress in shrinking sizes of semiconductor devicesand/or electronic components, more small devices and/or components areto be integrated into a given area, leading to high integration densityof various semiconductor devices and/or electronic components.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 to FIG. 7 are schematic cross-sectional views of various stagesin a manufacturing method of a semiconductor device in accordance withsome embodiments of the disclosure.

FIG. 8 to FIG. 10 are schematic top view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure.

FIG. 11 is a schematic perspective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure.

FIG. 12A is a schematic perspective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure.

FIG. 12B and FIG. 12C are schematic cross-sectional views of thestructure of FIG. 12A along the cross-section lines I-I and II-IIrespectively according to some exemplary embodiments of the disclosure.

FIG. 13 is a schematic cross-sectional view showing a capacitorstructure in accordance with some embodiments of the disclosure.

FIG. 14 is a schematic prospective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure.

FIG. 15 is a circuit diagram showing an inverter connected with acapacitor.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, values, operations, materials,arrangements, or the like, are described below to simplify thedisclosure. These are, of course, merely examples and are not intendedto be limiting. Other components, values, operations, materials,arrangements, or the like, are contemplated. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the disclosure may repeat reference numerals and/or letters inthe various examples. This repetition is for the purpose of simplicityand clarity and does not in itself dictate a relationship between thevarious embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

In addition, terms, such as “first,” “second,” “third,” “fourth,” andthe like, may be used herein for ease of description to describe similaror different element(s) or feature(s) as illustrated in the figures, andmay be used interchangeably depending on the order of the presence orthe contexts of the description.

It should be appreciated that the following embodiment(s) of the presentdisclosure provides applicable concepts that can be embodied in a widevariety of specific contexts. The specific embodiment(s) discussedherein is merely illustrative and is related to an integration structurecontaining more than one type of semiconductor devices, and is notintended to limit the scope of the present disclosure. Embodiments ofthe present disclosure describe the exemplary manufacturing process ofintegration structures formed with one or more semiconductor capacitorsand the integration structures fabricated there-from. Certainembodiments of the present disclosure are related to the structuresincluding semiconductor capacitors and other semiconductor devices.Other embodiments relate to semiconductor devices includingpolysilicon-insulator-polysilicon capacitor (PIP) structures located oninsulated isolation structure(s). The substrates and/or wafers mayinclude one or more types of integrated circuits or electroniccomponents therein. The semiconductor device(s) may be formed on a bulksemiconductor substrate or a silicon/germanium-on-insulator substrate.The embodiments are intended to provide further explanations but are notused to limit the scope of the present disclosure.

FIG. 1 to FIG. 7 are schematic cross-sectional views of various stagesin a manufacturing method of a semiconductor device in accordance withsome embodiments of the disclosure. From FIG. 1 through FIG. 7 , threeportions from the left to the right respectively represent the schematicviews of cross-sections along Y axis and X axis of an isolating regionIR and schematic cross-section views of an active region AR. FIG. 8 toFIG. 10 are schematic top views showing a portion of the structure inthe isolating region IR in accordance with some embodiments of thedisclosure. FIG. 11 is a schematic perspective view showing thestructure including a capacitor structure in the isolating region IR inaccordance with some embodiments of the disclosure.

Referring to FIG. 1 , in some embodiments, a substrate 100 having one ormore isolation structure 110 therein is provided. As shown in FIG. 1 ,in some embodiments, the isolation structures 110 define an activeregion AR and an isolating region IR separating and isolating the activeregion AR. In some embodiments, one or more active component such astransistors, diodes, optoelectronic devices or the like are formed inthe active region AR, while one or more passive components such ascapacitors are formed in the isolating region IR. In some embodiments,the substrate 100 includes a capacitor region formed with one or moresemiconductor capacitors in the isolating region IR. In someembodiments, the substrate 100 includes a transistor region formed withone or more transistors in the active region AR.

In some embodiments, the substrate 100 is a semiconductor substrate. Inone embodiment, the substrate 100 comprises a crystalline siliconsubstrate (e.g., wafer). In certain embodiments, the substrate 100 maybe a doped semiconductor substrate (e.g., p-type substrate or n-typesubstrate). In certain embodiments, the substrate 100 comprises one ormore doped regions or various types of doped regions, depending ondesign requirements. In some embodiments, the doped regions are dopedwith p-type and/or n-type dopants. For example of a non-limitingpurpose, the p-type dopants are boron or BF₂ and the n-type dopants arephosphorus or arsenic. The doped regions may be configured for an n-typemetal-oxide-semiconductor (MOS) transistor or a p-type MOS (PMOS)transistor. In some alternative embodiments, the substrate 100 is madeof other suitable elemental semiconductor, such as diamond or germanium;a suitable compound semiconductor, such as gallium arsenide, siliconcarbide, indium arsenide, or indium phosphide; or a suitable alloysemiconductor, such as silicon germanium carbide, gallium arsenicphosphide, or gallium indium phosphide.

As shown in FIG. 1 , in some embodiments, more than one isolationstructure 110 is formed in the substrate 100. In certain embodiments,the isolation structures 110 are trench isolation structures. Theformation of the trench isolation structures includes partially coveringthe substrate 100 with a photoresist pattern (not shown), patterning thesubstrate 100 to form trenches in the substrate 100 and filling thetrenches with an insulator material. For example, the photoresistpattern includes a predetermined pattern with openings corresponding tothe predetermined locations of the isolation structures. In someembodiments, as shown in FIG. 1 , top surfaces 111 of the isolationstructures 110 are substantially leveled with the top surface 100S ofthe substrate 100. In some embodiments, the top surface 100S of thesubstrate 100 is substantially leveled with the top surface 111 of theisolation structure 110. In one embodiment, after filling the insulatormaterial in the trenches, a planarization process such as a mechanicalgrinding process or chemical mechanical polishing process is performedto remove extra insulator material. In some embodiments, the insulatormaterial of the isolation structures 110 includes silicon oxide, siliconnitride, silicon oxynitride, a spin-on dielectric material, or a low-kdielectric material. In one embodiment, the insulator material of theisolation structures 110 may be formed by high-density-plasma chemicalvapor deposition (HDP-CVD), sub-atmospheric CVD (SACVD) or by spin-on.

The number of the isolation structures 110 shown in FIG. 1 is merely forillustration, in some alternative embodiments, more than two isolationstructures may be formed in accordance with actual design requirements.In some embodiments, the isolation structures 110 include shallow trenchisolation structures. In other embodiments, the isolation structures 110includes local oxidation of silicon (LOCOS) structures. In someembodiments, the isolation structures 110 are shaped as rings, strips orblocks and arranged aside the active region(s) or in parallel, and it isunderstood that the shape(s) and size(s) of the isolation structures arenot limited by the embodiments herein. In one embodiment, an optionalcleaning process may be performed to remove a native oxide of thesubstrate 100. The cleaning process may be performed using dilutedhydrofluoric (DHF) acid or other suitable cleaning solutions. In oneembodiment, an isolation implantation process may be performed tostrengthen the isolation effects.

Referring to FIG. 1 , a diffusion region 120 is formed in the substrate100 within the active region AR (e.g. within the transistor region). Thediffusion region 120 is a well region doped with dopants of oneconductive type. In some embodiments, the diffusion region 120 is anN-type well (N-well) region. In one embodiment, the diffusion region 120is doped with phosphorus as an N-well region for a PMOS transistorfollowing the CMOS processes. In some embodiments, the diffusion region120 is a P-type well region (P-well) region. In one embodiment, thediffusion region 120 is doped with boron as a P-well region for an NMOStransistor following the CMOS processes. In certain embodiments, thediffusion region(s) 120 is formed by performing ion implantation to theexposed substrate 100 using a photoresist pattern (not shown) partiallycovering the substrate 100 as the mask, and a thermal process isperformed to further drive the dopants into the substrate to form thediffusion region 120. In one embodiment, the diffusion region 120 isformed in the regions exposed by the photoresist pattern and thediffusion region 120(s) is formed only in the active region AR. In someembodiments, the diffusion region 120 is deeper than the isolationstructure(s) 110. That is, the depth of the isolation structure 110(measuring from the top surface 100S of the substrate 100) is smallerthan the depth of the diffusion region 120.

In some embodiments, a dielectric pattern 132 and a semiconductormaterial pattern 134 are formed over the substrate 100 and on thediffusion region 120 in the active region AR as shown in the rightportion of FIG. 2 , while the semiconductor material patterns 135, 136are formed over the substrate 100 and on the isolation structures 110 inthe isolating region IR as shown in the middle and left portions of FIG.2 . In some embodiments, the formation of the dielectric pattern 132includes forming a mask pattern (not shown) protecting the isolatingregion IR, forming a dielectric material layer (not shown) covering theactive region AR of the substrate 100 and patterning the dielectricmaterial layer to form the dielectric pattern 132 in the active regionAR. In one embodiment, the dielectric material for forming thedielectric pattern 132 includes an oxide material such as silicon oxide.In one embodiment, the dielectric material for forming the dielectricpattern 132 includes silicon oxide, silicon nitride, silicon oxynitrideor combinations thereof. In some embodiments, the formation of thesemiconductor material patterns 134, 135, 136 includes forming asemiconductor material blanketly over the substrate 100 and patterningthe semiconductor material to form the semiconductor material pattern(s)134 in the active region AR and to form the semiconductor materialpatterns 135, 136 in the isolating region IR. In the embodiments, thesemiconductor material for forming the semiconductor material patterns134, 135, 136 includes doped or undoped polysilicon. The semiconductormaterial may be formed by chemical vapor deposition (CVD) such aslow-pressure CVD (LPCVD) or plasma-enhanced CVD (PECVD) orcrystallization or amorphous silicon.

In certain embodiments, as shown in the right portion of FIG. 2 , thesemiconductor material is deposited on the dielectric material layer inthe active region AR, and the patterning of the dielectric materiallayer and the semiconductor material may include performing one or moreetching processes to etch the dielectric material layer and thesemiconductor material using the same mask pattern, at the same time orin sequence. In some embodiments, the semiconductor material pattern 134and dielectric pattern 132 are patterned into a stacked strip structure130 in the active region AR. In one embodiment, the stacked structure130 may function as a gate stack, and the semiconductor material pattern134 and dielectric pattern 132 function as the gate electrode and gatedielectric layer of the stacked structure 130.

In certain embodiments, as shown in the left and middle portions of FIG.2 , the semiconductor material is deposited over the substrate 100 anddirectly on the isolation structure(s) 110 in the isolating region IR,and the patterning of the semiconductor material may include performingone or more etching processes to etch the semiconductor material. Insome embodiments, the semiconductor material formed in the active regionAR and in the isolating region IR is patterned in the same process. Insome embodiments, the semiconductor material formed in the active regionAR and in the isolating region IR is patterned individually throughdifferent processes.

FIG. 8 is a schematic top view showing a portion of the structureincluding the patterned structures 135 and 136 in accordance with someembodiments of the disclosure. In some embodiments, referring to FIG. 8, the semiconductor material patterns 136 and 135 are shaped as a ringstructure and an islet structure surrounded by the ring structure butwith a gap or space G in-between. The semiconductor material pattern 135is spaced apart from the ring structure of the semiconductor materialpattern 136 with a distance D1 in Y axis direction and a distance D2 inX axis direction. In one embodiment, the ring structure of thesemiconductor material pattern 136 includes portions 136Y of thesemiconductor material pattern 136 extending in Y axis (Y-portions) andportions 136X of the semiconductor material pattern 136 extending in Xaxis (X-portions). In one embodiment, the Y-portion 136Y has a width W2smaller than the width W1 of the X-portions 136X. In another embodiment,the Y-portion 136Y has a width W2 larger than the width W1 of theX-portions 136X. In another embodiment, the Y-portion 136Y has a widthW2 substantially equivalent to the width W1 of the X-portions 136X.

In some other embodiments, the semiconductor material in the isolatingregion IR may be patterned into more than one strip structures arrangedsubstantially in parallel.

In some embodiments, the semiconductor material patterns 134, 135 and136 are formed from patterning the same layer of semiconductor materialin the active region AR and the isolating region IR. That is, thematerial of the semiconductor material patterns 134, 135 and 136 is thesame. In addition, the formation of the semiconductor material patterns135 and 136 may be accomplished through some or parts of the processesfor forming the gate stacked structure in the CMOS process.

In some embodiments, as shown in right portions of FIG. 3 , lightlydoped drain (LDD) regions 140 are formed within the diffusion region120, in the substrate 100, at both opposite sides of the stackedstructure 130 and within the active region AR (e.g. within thetransistor region). In certain embodiments, the LDD regions 140 arelightly doped regions with dopants of a conductive type that isdifferent from the conductive type of the diffusion region 120. In someembodiments, the diffusion region 120 is an N-well region, and the LDDregions 140 are P-type lightly doped regions. In some embodiments, thediffusion region 120 is a P-well region, and the LDD regions 140 areN-type lightly doped regions. In one embodiment, the LDD regions 140 arelightly doped with dopants as LDD regions for NMOS and/or PMOStransistors following the CMOS processes. After the formation of the LDDregions 140, the photoresist pattern PR1 is removed.

In one embodiment, the LDD regions 140 have a first dopingconcentration. In certain embodiments, as shown in FIG. 3 , the LDDregions 140 are formed in the active region AR by performing ionimplantation to the exposed substrate 100 using the stacked structure130 and photoresist pattern PR1 partially covering the isolationstructures 110 as the masks. In one embodiment, the LDD regions 140 areformed only in the active region AR. In some embodiments, the LDDregions 140 are shallower than the isolation structure(s) 110 and thediffusion region 120. In certain embodiments, under the condition thatthe LDD regions 140 are N-type lightly doped regions for fabricating theNMOS transistor, N-type dopants such as phosphorous atoms may be dopedwith a dopant concentration ranging from 1*10¹³ to 1*10¹⁵ atoms persquare centimeter, and the ion implanting process may provide a dopingenergy of 20 to 100 keV, for example of a non-limiting purpose.

In some embodiments, the LDD regions 140 are formed in the substrate 100and along sidewalls 130S of the stacked structure 130. In someembodiments, the LDD regions 140 formed at both opposite sides of thestacked structure 130 are symmetric LDD regions having the same dopingconcentration and the same extension width. In alternative embodiments,the LDD regions 140 formed at both opposite sides of the stackedstructure 130 are asymmetric LDD regions with different extensionwidths. In general, leakage current and hot carrier effect can beeffectively improved by forming the LDD regions in the transistors.

FIG. 9 is a schematic top view showing a portion of the structureincluding the patterned structures 135 and 136 in accordance with someembodiments of the disclosure. In some embodiments, as shown in left andmiddle portions of FIG. 3 , the semiconductor material pattern 136 inthe isolating region IR is lightly doped into lightly doped portions136A. In the left portion of FIG. 3 , the X-portions 136X are partiallydoped to form the lightly doped portions 136A, while the Y-portions 136Yare doped into lightly doped portions 136A as shown in the middleportion of FIG. 3 . In one embodiment, the lightly doped portions 136Aare formed in the isolating region IR through the same ion implantationprocess for forming the LDD regions 140 in the active region AR. Incertain embodiments, the lightly doped portions 136A are formed in theregions exposed by the photoresist pattern PR1 and the lightly dopedportions 136A are formed only in the isolating region IR. In oneembodiment, the photoresist pattern PR1 protects the semiconductormaterial pattern 135 and portions of the semiconductor material pattern136 from being implanted, so that the lightly doped portions 136A areformed by doping the Y-portions 136Y and parts of the X-portions 136X.Referring to FIG. 3 and FIG. 9 , the ring structure of the semiconductormaterial pattern 136 includes the lightly doped portions 136A (as a ringstructure in FIG. 9 ) and undoped portions 136U of X-portions 136X. Insome embodiments, the semiconductor material pattern 135 is not doped inthe ion implantation process for forming the LDD regions 140 and thelightly doped portions 136A.

In some embodiments, the lightly doped portions 136A and the undopedportion 136U in the isolating region IR and the LDD regions 140 in theactive region AR are formed from the same ion implantation process. Thatis, the same doping conditions may be used and the doping concentrationsin these portions/regions are the same. In some embodiments, the lightlydoped portions 136A have substantially the same doping concentration asthe first doping concentration of the LDD regions 140. In addition, theformation of the light doped portions 136A and the undoped portion 136Umay be accomplished through some or parts of the processes for formingthe LDD regions in the CMOS process.

As shown in FIG. 4 , in some embodiments, spacers 150 are formed on thesidewalls 130S of the stacked structure 130 in the active region AR, andspacers 150 are formed on sidewalls of the semiconductor materialpatterns 135 and 136. In certain embodiments, the formation of thespacers 150 includes forming a spacer material layer (not shown) overthe substrate 100, conformally covering the stacked strip structure 130and conformally covering the semiconductor material patterns 135 and136, and etching back the spacer material layer to form the spacers 150.In some embodiments, the spacer material layer is formed of one or moredielectric materials, such as silicon oxide, silicon nitride, siliconcarbon oxynitride (SiCON), silicon carbonitride (SiCN) or combinationsthereof. In some embodiments, the spacers 150 may be a single layer or amultilayered structure.

In some embodiments, the spacers 150 formed on the sidewalls 130S of thestacked structure 130 in the active region AR and formed on sidewalls ofthe semiconductor material patterns 135 and 136 in the isolating regionIR are formed from the same spacer material layer and through the sameetching back process. In some other embodiments, the spacers 150 areformed only on the sidewalls 130S of the stacked structure 130 in theactive region AR, while no spacers 150 are formed on sidewalls of thesemiconductor material patterns 135 and 136, as the isolating region IRmay be masked during the formation of the spacers 150.

In some embodiments, referring to right portion of FIG. 5 , source anddrain (S/D) regions 160 are formed within the diffusion region 120, inthe substrate 100, at both opposite sides of the stacked structure 130and within the active region AR (e.g. within the transistor region). Incertain embodiments, the S/D regions 160 are heavily doped regions withdopants of a conductive type that is the same as that of the LDD region140 but is different from that of the diffusion region 120. In someembodiments, the diffusion region 120 is an N-well region, and the S/Dregions 160 are P-type heavily doped regions. In some embodiments, thediffusion region 120 is a P-well region, and the S/D regions 160 areN-type heavily doped regions. In one embodiment, the S/D regions 160 areheavily doped with dopants as source and drain regions for NMOS and/orPMOS transistors following the CMOS processes. In one embodiment, afterthe formation of the S/D regions 160, the photoresist pattern PR2 isremoved.

In one embodiment, the S/D regions 160 have a second dopingconcentration larger than the first doping concentration of the LDDregions 140. In certain embodiments, as shown in FIG. 5 , the S/Dregions 160 are formed in the active region AR by performing ionimplantation to the exposed substrate 100 using the spacers 150, thestacked structure 130 and photoresist pattern PR2 partially covering theisolation structures 110 as the masks. In one embodiment, the S/Dregions 160 are formed only in the active region AR. In someembodiments, the S/D regions 160 are shallower than the isolationstructure(s) 110 and the diffusion region 120 but are deeper than theLDD regions 140. In certain embodiments, under the condition that theS/D regions 160 are N-type heavily doped regions for fabricating theNMOS transistor, N-type dopants such as phosphorous atoms may be dopedwith a dopant concentration ranging from 1*10¹⁵ to 1*10¹⁶ atoms persquare centimeter, the ion implanting process may provide a dopingenergy of 3 to 50 keV, for example of a non-limiting purpose. In oneembodiment, during the ion implantation process, the semiconductormaterial pattern 134 of the stacked structure 130 is also doped andbecomes the doped semiconductor material pattern 134B.

In some embodiments, the S/D regions 160 are formed in the substrate 100and along outer sidewalls of the spacers 150 beside the stackedstructure 130. In certain embodiments, a channel region 145 ispositioned in the substrate 100 (within the diffusion region 120)between the S/D regions 160 and under the stacked structure 130, and theS/D regions 160 are positioned beside the channel region 145. In someembodiments, the S/D regions 160 formed at both opposite sides of thestacked structure 130 are symmetric source and drain regions having thesame doping concentration and the same extension width. In alternativeembodiments, the S/D regions 160 formed at both opposite sides of thestacked structure 130 are asymmetric source and drain regions withdifferent extension widths.

FIG. 10 is a schematic top view showing a portion of the structureincluding the patterned structures 135B and 136 in accordance with someembodiments of the disclosure. In some embodiments, as shown in left andmiddle portions of FIG. 5 , the semiconductor material pattern 135 andthe undoped portions 136U (FIG. 3 & FIG. 9 ) in the isolating region IRare doped respectively into heavily doped portions 135B and 136B. In theleft portion of FIG. 5 , the X-portions 136X are partially doped to formthe heavily doped portions 136B, while the lightly doped portions 136Aof the X-portions 136X are not further doped and remain lightly doped.As shown in the middle portion of FIG. 5 , the Y-portions 136Y are notfurther doped and remain to be lightly doped portions 136A, but theuncovered semiconductor material pattern 135 is heavily doped into theheavily doped portion 135B. In one embodiment, the heavily dopedportions 135B and 136B are formed in the isolating region IR through thesame ion implantation process for forming the S/D regions 160 in theactive region AR. In certain embodiments, the heavily doped portions135B and 136B are formed in the regions exposed by the photoresistpattern PR2 and the heavily doped portions 135B and 136B are formed onlyin the isolating region IR. In one embodiment, the photoresist patternPR2 protects the lightly doped portions 136A but exposes thesemiconductor material pattern 135 and portions of the semiconductormaterial pattern 136, so that the heavily doped portions 135B and 136Bare formed by doping the semiconductor material pattern 135 and undopedportions 136U. Referring to FIG. 5 and FIG. 10 , the ring structure ofthe semiconductor material pattern 136 includes the lightly dopedportions 136A (as a ring structure in FIG. 10 ) and heavily dopedportions 136B of X-portions 136X. In some embodiments, the semiconductormaterial pattern 135 is doped into the heavily doped portion 135B duringthe ion implantation process for forming the S/D regions 160 and theheavily doped portions 136B.

In some embodiments, the heavily doped portions 135B and 136B in theisolating region IR and the S/D regions 160 in the active region AR areformed from the same ion implantation process. That is, the same dopingconditions may be used and the doping concentrations in theseportions/regions are the same. In some embodiments, the heavily dopedportions 135B and 136B have substantially the same doping concentrationas the second doping concentration of the S/D regions 160. In addition,the formation of the heavily doped portions 135B and 136B may beaccomplished through some or parts of the processes for forming thesource and drain regions in the CMOS process.

Referring to FIG. 6 , in some embodiments, silicide top layers 170 areformed on the doped semiconductor material pattern 134, the S/D regions160 and on the heavily doped portions 135B and 136B by silicidation. Insome embodiments, a self-aligned silicide (salicide) process is usuallyincluded in a MOS transistor process to reduce the resistance of the S/Dregions and silicon gates. In one embodiment, the salicide processincludes forming a layer of refractory metal over the substrate 100,thermally reacting the silicon or semiconductor material at the surfacesof S/D regions and of the semiconductor material patterns with the metalto form a metal silicide layer and then removing the unreacted metal. Incertain embodiments, the photoresist pattern PR2 is not removed untilthe self-aligned silicide process is finished. In some embodiments, theregions that are not intended to be formed with silicide are protectedby a masking material (not shown), which is later removed. In someembodiments, the material of the silicide top layer 170 is, for exampleof a non-limiting purpose, a silicide of Ni, Co, Ti, Cu, Mo, Ta, W, Er,Zr, Pt, Yb, Gd, Dy or an alloy of any two thereof. In one embodiment,the material of the silicide top layer 170 is titanium silicide, cobaltsilicide, nickel silicide or nickel platinum silicide.

Referring to FIG. 7 , in some embodiments, an inter-layer dielectric(ILD) layer 180 is formed as a blanket layer over the substrate 100 tofully cover the stacked structure 130, the S/D regions 160 and theisolation structures 110 in the active region AR, and to fully cover theportions 135B, 136A and 136B in the isolating region IR. In oneembodiment, the material of the ILD layer 180 may include silicon oxide.In one embodiment, the material of the ILD layer 180 may includesilicate glass such as phospho-silicate-glass (PSG) andboro-phospho-silicate-glass (BPSG). In one embodiment, the material ofthe ILD layer 180 may include a low-k dielectric material. In certainembodiment, the ILD layer 180 may further be planarized and covered by apassivation layer (not shown) thereon.

FIG. 11 is a schematic perspective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure. The structure of FIG. 11 may befabricated following the process steps depicted from FIG. 1 to FIG. 5and FIG. 7 . Only a portion of the structure in the isolating region IRis shown in FIG. 11 . As shown in FIG. 11 , the structure includesspacers 150 formed on sidewalls of the portions 135B, 136A and 136B,while the locations for the to-be formed contacts are labelled CT. InFIG. 11 , the lightly doped portions 136A form a ring-shaped structure,and the heavily doped portion 135B is located in the middle of thering-shaped structure like an islet and spaced apart from thering-shaped structure. In FIG. 11 , the ILD layer 180 is formed betweenthe lightly doped portions 136A and the heavily doped portions 136B. TheILD layer 180 is also formed outside the ring-shaped structure of thelightly doped portions 136A and the heavily doped portions 136B.

FIG. 12A is a schematic perspective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure. The structure of FIG. 12A may befabricated following the process steps depicted in FIG. 1 to FIG. 3 ,FIG. 5 and FIG. 7 . FIG. 12B and FIG. 12C are schematic cross-sectionalviews of the structure of FIG. 12A along the cross-section lines I-I andII-II respectively according to some exemplary embodiments of thedisclosure. That is, neither the spacer nor the silicide layer(s) ispresent in FIG. 12A through FIG. 12C for illustration purposes.

Then, as shown in FIG. 7 , in some embodiments, a plurality of contacts190 is formed in the ILD layer 180. In some embodiments, the contacts190 are connected to the silicide top layers 170 on the dopedsemiconductor material pattern 134, the S/D regions 160 and on theheavily doped portions 135B and 136B, respectively. In some embodiments,the formation of the contacts 190 includes forming a patterned masklayer (not shown) over the ILD layer and dry etching the ILD layer usingthe patterned mask layer as a mask to form openings exposing thesilicide top layers 170. In certain embodiments, the ILD layer 180 mayfurther include an etch stop layer (not shown) therein. Thereafter, aconductive material is deposited and filled into the contact openings toform the contacts 190. The conductive material is a metal layerincluding aluminum, copper, tungsten, or alloys thereof, and theconductive material may be formed by performing a CVD process, forexample.

In alternative embodiments, the ILD layer 180 formed in the isolatingregion may further include an optional insulator material (not shown)filled between the portions 135B, 136A and 136B in the isolating regionIR. The formation of the insulator material includes sequentiallydepositing a silicon oxide layer, a silicon nitride layer and a siliconoxide layer covering and filling between the portions 135B, 136A and136B in the isolating region IR.

In some embodiments, as shown in the left and middle portions of FIG. 7, the ILD layer 180 fills up the gaps/spaces G between the portions135B, 136A and 136B in the isolating region IR. As shown in FIG. 7 &FIG. 12A, the portions 135B, 136A and 136B located on the isolationstructure(s) 110 and the ILD layer 180 filled between the portions 135B,136A and 136B constitute a capacitor structure 10C. In FIG. 12A, the ILDlayer 180 fills between the heavily doped portion 135B and thering-shaped structure that includes the lightly doped portions 136A andheavily doped portions 136B. As shown in FIG. 12A through FIG. 12C, thecapacitor structure 10C is a horizontal structure overlying on the topsurface 111 (as the horizontal plane) of the isolation structure 110. Incertain embodiments, when the semiconductor material is polysilicon, thecapacitor structure 10C includes the portions 135B, 136A and 136B as thepolysilicon parts and the ILD layer 180 filled between the portions135B, 136A and 136B as the insulator part (ID) of apolysilicon-insulator-polysilicon (PIP) capacitor structure arrangedalong the horizontal plane. In some embodiments, the interface IF1between the lightly doped portion 136A and the insulator part ID (theILD layer 180) is substantially perpendicular to the horizontal plane ofthe top surface 111 of the isolation structure 110. In some embodiments,the interface IF2 between the heavily doped portion 135B and theinsulator part ID (the ILD layer 180) is substantially perpendicular tothe horizontal plane of the top surface 111 of the isolation structure110. If considering the portions 135B, 136B and 136A packed with theinsulator portion ID are arranged at the same level (same horizontallevel) and directly on the isolation structure 110, such configurationof the capacitor structure 10C is very different from the verticallystacked three layered capacitor structure. That is, the capacitorstructure 10C may be considered as a horizontal-type capacitor.

Referring to FIG. 12B and FIG. 12C, the heavily doped portion 135B, thelightly doped portion 136A and the insulating ILD layer 180 sandwichedthere-between may function as the gate, the bulk (lightly doped body)and the insulator of a polysilicon insulator polysilicon (PIP)capacitor. The doping characteristics of the PIP capacitor electrodeplates lead to capacitance variations, with changes in the capacitanceas a function of applied voltage. When the dopant types (or dopantconcentrations) of the electrode plates, i.e., the heavily doped portion135B and the lightly doped portion 136A, are different, the PIPcapacitor is a variable capacitor. The capacitance of the PIP capacitorincreases with the voltage applied to the gate. In one embodiment, whenthe heavily doped portions 135B and 136B are N-type heavily dopedportions, and the lightly doped portion 136A is an N-type lightly dopedportion, the capacitor is a variable capacitor. In one embodiment, whenthe heavily doped portion 135B is an N-type heavily doped portion, theheavily doped portions 136B are P-type heavily doped portions, and thelightly doped portion 136A is a P-type lightly doped portion, thecapacitor is a variable capacitor. In one embodiment, when the heavilydoped portion 135B is a P-type heavily doped portion, the heavily dopedportions 136B are N-type heavily doped portions, and the lightly dopedportion 136A is an N-type lightly doped portion, the capacitor is avariable capacitor. In one embodiment, when the heavily doped portions135B and 136B are P-type heavily doped portions, and the lightly dopedportion 136A is a P-type lightly doped portion, the capacitor is avariable capacitor.

Following the previous processes according to some embodiments, thesemiconductor material layer or the polysilicon layer used for formingthe gate electrode for MOS transistors is also used to form the heavilydoped portion 135B, the lightly doped portion 136A, which are functionedas upper and lower electrodes of a PIP capacitor. In some embodiments,portions of the semiconductor material layer or the polysilicon layerserved as the upper electrode may be doped with source/drain implants,while other portions of the semiconductor material layer or thepolysilicon layer served as the lower electrode may be doped with LDDimplants.

As shown in FIG. 12B and FIG. 12C, the lightly doped portion 136A isspaced apart from the heavily doped portion 135B with a distance D3 inthe X axis direction and with a distance D4 in the Y-axis direction. Asthe insulating ILD layer 180 is filled between the space between theportions 135B and 136A, the ILD layer 180 filled between the portions135B and 136A is formed with a thickness in the X axis directionequivalent to D3 and a thickness in the Y-axis direction equivalent toD4. Since the capacitor structure 10C is a horizontal-type capacitor,the thickness of the insulator can be easily tuned by modifying thedistance between the heavily doped portion 135B and the lightly dopedportion 136A. Therefore, based on the product requirements, thecapacitance of the capacitor structure can be designed or tuned throughthe modification of the layout or configuration of the semiconductormaterial patterns during the MOS manufacturing processes. In this case,there is no need to use additional mask(s) and perform additionalprocesses to specifically form the gate oxide of different thicknesses,especially thicker gate oxide, for the formation of the capacitorstructure. Also, the insulator or dielectric integrity of thehorizontal-type capacitor is improved as the localized thinning of theinsulator is reduced. Accordingly, the horizontal-type capacitorstructure may be formed without the need of forming an additionpolysilicon layer and/or performing extra implantation processes. Theformation of the capacitor structure is compatible with the CMOSmanufacturing processes and is more cost-effective. Further, thecapacitor structure is formed in the non-active region or the isolatingregion and is located on the isolation structure(s), more layout area issaved for forming active components.

In another embodiments, as shown in FIG. 13 , the capacitor structure13C is located on the isolation structure IS and has a ring-shapedheavily doped portion HP2 and a heavily doped portion HP1 located in themiddle of and spaced apart from the heavily doped portion HP2. Also, thecapacitor structure 13C has an insulator portion ID sandwiched andlocated between the heavily doped portions HP1 and HP2. The ring-shapedheavily doped portion HP2 functions similarly to the heavily dopedportion 136B shown in FIG. 12A. The heavily doped portion HP1 functionssimilarly to the heavily doped portion 135B shown in FIG. 12A. Differentfrom the structure of FIG. 12A, the capacitor structure of FIG. 13 hasno lightly doping portion. When the heavily doped portions HP1 and HP2are of the same conductive type and have the same doping concentration,the capacitor structure 13C serves as a constant capacitor.

FIG. 14 is a schematic prospective view showing a portion of thestructure including a capacitor structure in accordance with someembodiments of the disclosure. Referring to FIG. 14 , in someembodiments, the capacitor structure 14C is a horizontal type capacitorand is located on the isolation structure IS. In some embodiments, thestructure 14C includes a first heavily doped portion HP1 and a secondheavily doped portion HP2. The first and second heavily doped portionsare shaped as strip structures and arranged in parallel. In someembodiments, the structure 14C includes a lightly doped portion LPlocated next to the second heavily doped portion HP2 and located betweenthe first and second heavily doped portions HP1 and HP2. Also, thecapacitor structure 14C has an insulator portion ID sandwiched betweenthe lightly doped portion LP and the first heavily doped portion HP1 andlocated between the heavily doped portions HP1 and HP2. The firstheavily doped portion HP1 and the second heavily doped portion HP2function similarly to the heavily doped portion 135B, 136B shown in FIG.12A. The lightly doped portion LP functions similarly to the lightlydoped portion 136A shown in FIG. 12A. Thus, the capacitor structure 14Cfunctions as a MOS capacitor, and has a variable capacitance in responseto a varied bias.

Following the previous processes according to some embodiments, thelightly and heavily doped portions of the capacitor structure 14C may beformed from the semiconductor material layer or the polysilicon layerused for forming the gate electrode for MOS transistors. In someembodiments, the heavily doped portions HP1 and HP2 may be doped withsource/drain implants, while the lightly doped portion may be doped withLDD implant.

FIG. 15 is a circuit diagram showing an inverter 1500 connected with acapacitor C. In one exemplary embodiment, the inverter 1500 includes aP-type MOS (PMOS) transistor 1502 and an N-type MOS (NMOS) transistor1504. In FIG. 15 , the PMOS transistor 1502 is electrically connected topower or high voltage supply HV V_(dd), while the NMOS transistor 1504is electrically connected to the ground GND. The capacitor C isconnected with the output terminal and also connected to the ground GND.In some embodiments, the capacitor C is a constant capacitor and iselectrically connected with the inverter 1500. In certain embodiments,the capacitor C includes or is formed of the capacitor structure(s) asdescribed in the above contexts. In one embodiment, the capacitor C hasupper and lower electrodes E1 and E2, which are similar to the heavilydoped portions HP1 and HP2 of the capacitor structure 13C shown in FIG.13 . In one embodiment, the capacitor C has upper and lower electrodesE1 and E2, which are similar to the heavily doped portion 135B and thelightly doped portion 136A of the capacitor structure 10C shown in FIG.12A. As described herein, the possible applications of the capacitorstructures are not limited by the embodiments provided herein, and thecapacitor structures may be applicable for any circuitry or used incombination with different electronic devices.

In accordance with some embodiments, a method of manufacturing asemiconductor device includes forming an isolation structure in asubstrate to define an isolating region and forming a capacitorstructure on an upper surface of the isolation structure and comprisinga first semiconductor structure and a second semiconductor structureseparated by an insulator pattern. The first semiconductor structure andthe second semiconductor structure are formed with upper surfacesaligned with one another.

In accordance with some other embodiments, a method of manufacturing asemiconductor device includes forming an isolation structure in asubstrate to define an isolating region and forming a firstsemiconductor structure and a second semiconductor structure on an uppersurface of the isolation structure. The method further comprises formingan insulator pattern between and separating the first semiconductorstructure and the second semiconductor structure. The firstsemiconductor structure comprises a lightly doped portion closer to theinsulator pattern and a heavily doped portion farther from the insulatorpattern. The lightly doped portion has a doping concentration lower thanthat of the heavily doped portion.

In accordance with some further embodiments, a method of manufacturing asemiconductor device includes forming an isolation structure in asubstrate to define an isolating region and forming a semiconductormaterial pattern on the isolation structure. The method further includesforming a lightly doped portion with a first doping concentration in thesemiconductor material pattern by performing a first ion implantationprocess to the semiconductor material pattern in the isolating region.The method further includes forming at least one heavily doped portionin the semiconductor material pattern by performing a second ionimplantation process to the semiconductor material pattern in theisolating region. The at least one heavily doped portion has a dopingconcentration higher than the first doping concentration. The methodfurther includes forming an insulator material layer over the substratecovering the semiconductor material pattern in the isolating region. Theinsulator material layer at least fills up a gap of the semiconductormaterial pattern.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the disclosure.Those skilled in the art should appreciate that they may readily use thedisclosure as a basis for designing or modifying other processes andstructures for carrying out the same purposes and/or achieving the sameadvantages of the embodiments introduced herein. Those skilled in theart should also realize that such equivalent constructions do not departfrom the spirit and scope of the disclosure, and that they may makevarious changes, substitutions, and alterations herein without departingfrom the spirit and scope of the disclosure.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: forming an isolation structure in a substrate to define anisolating region; forming a capacitor structure on an upper surface ofthe isolation structure and comprising a first semiconductor structureand a second semiconductor structure separated by an insulator pattern;and wherein the first semiconductor structure and the secondsemiconductor structure are formed with upper surfaces aligned with oneanother.
 2. The method of claim 1, wherein the insulator pattern isformed with an upper surface aligned with the upper surfaces of thefirst semiconductor structure and the second semiconductor structure. 3.The method of claim 1, wherein the insulator pattern is formed with aring shape and encompassing the second semiconductor structure.
 4. Themethod of claim 3, wherein forming the first semiconductor structurecomprises forming a lightly doped portion contacting the insulatorpattern and a heavily doped portion on one side of the lightly dopedportion opposite to the insulator pattern, the lightly doped portionhaving a doping concentration lower than that of the heavily dopedportion.
 5. The method of claim 4, wherein the lightly doped portion isformed with a ring shape enclosing an outer periphery of the insulatorpattern.
 6. The method of claim 4, wherein the heavily doped portion isformed with strip structures arranged at opposite sides the lightlydoped portion and contacting the lightly doped portion.
 7. The method ofclaim 4, wherein the second semiconductor structure is heavily dopedwith the same doping concentration of the heavily doped portion of thefirst semiconductor structure.
 8. The method of claim 1, wherein thesecond semiconductor structure is formed with directly contacting theinsulator pattern.
 9. The method of claim 1, wherein the firstsemiconductor structure, the second semiconductor structure, and theinsulator pattern are formed with strip structures with the same lengthand arranged in parallel.
 10. The method of claim 1, wherein theinsulator pattern is formed with a ring shape, and wherein the firstsemiconductor structure is formed enclosing an outer periphery of theinsulator pattern.
 11. The method of claim 1, wherein the firstsemiconductor structure, the second semiconductor structure, and theinsulator pattern are formed with strip structures.
 12. The method ofclaim 1, further comprising forming spacers on sidewalls of the firstsemiconductor structure and the second semiconductor structure.
 13. Amethod of manufacturing a semiconductor device, comprising: forming anisolation structure in a substrate to define an isolating region;forming a first semiconductor structure and a second semiconductorstructure on an upper surface of the isolation structure; and forming aninsulator pattern between and separating the first semiconductorstructure and the second semiconductor structure; and wherein the firstsemiconductor structure comprises a lightly doped portion closer to theinsulator pattern and a heavily doped portion farther from the insulatorpattern, the lightly doped portion having a doping concentration lowerthan that of the heavily doped portion.
 14. The method of claim 13,wherein the first semiconductor structure and the second semiconductorstructure are formed with a first interface of the first semiconductorstructure and the insulator pattern and a second interface of the secondsemiconductor structure and the insulator pattern substantiallyperpendicular to the upper surface of the isolation structure.
 15. Themethod of claim 13, wherein the insulator pattern is formed enclosing aperiphery of the second semiconductor structure, and wherein the firstsemiconductor structure is formed enclosing an outer periphery of theinsulator pattern.
 16. The method of claim 13, wherein the insulatorpattern, the first semiconductor structure, and the second semiconductorstructure are formed with bottom surfaces aligned from one another. 17.A method of manufacturing a semiconductor device, comprising: forming anisolation structure in a substrate to define an isolating region;forming a semiconductor material pattern on the isolation structure;forming a lightly doped portion with a first doping concentration in thesemiconductor material pattern by performing a first ion implantationprocess to the semiconductor material pattern in the isolating region;forming at least one heavily doped portion in the semiconductor materialpattern by performing a second ion implantation process to thesemiconductor material pattern in the isolating region, wherein the atleast one heavily doped portion has a doping concentration higher thanthe first doping concentration; and forming an insulator material layerover the substrate covering the semiconductor material pattern in theisolating region, wherein the insulator material layer at least fills upa gap of the semiconductor material pattern.
 18. The method of claim 17,further comprising forming a transistor in an active region of thesubstrate, wherein the first ion implantation process is performed toform the lightly doped portion in the semiconductor material pattern andlightly doped regions in the transistor in the same implantationprocess.
 19. The method of claim 18, wherein the second ion implantationprocess is performed to form the at least one heavily doped portion inthe semiconductor material pattern and source and drain regions in thetransistor in the same implantation process.
 20. The method of claim 17,wherein forming the semiconductor material pattern comprises forming asemiconductor material directly on a top surface of the isolationstructure, and forming the insulator material layer comprises forming aninsulator material filling into the gap of the semiconductor materialpattern and in contact with the top surface of the isolation structure.